Armor plate and process of making same



. es of ,Making iARMOR PLATE AND PROCESS.

. No Drawing} Since theiequipment' of war vessels with ron armor plate designed to resist penetration by cast contest -has. b and projectiles, the manufacturer of each product endeavouring to 'overcomethesuccessive improvementsgmade by, the .manu facturer of, the'other product. present the highest type of -armor, t'generally'in use is the cemented, face-hardened, back-tough- 1,,nicke rc 0me P lVithi'this platejithe object is to break the point of the projectile on a'face of intense I e face of the p ate, and which, by dislodglng the exceed ly hard and correspondingly brittle face, exposes the soft back to ready perforation.

In t e penetration of a soft, homogeneous steel plate by a projectile, the anterior surface of the plate is not thrown off as with a carburized, hard-faced plate, but is crowded asi e and to th forward, sprlngs up from the face of the plate in a serrated ring, which is the more pronounced the tougher the material.

Ve have found that with projectiles of the present improved type, a greater resistance to penetration is offered by a plate tleness and a large portion of v the greater stiffness carbon material forming the high - ;App1ica ti,on aiea June 27, 1922.

Same, of which the following e accompanying iron shot, a never ceasing b een waged between armor plate or Martins. SAME. Serial No. 571,301 Aplate of the type to which tion is applicable may be produced, for. example, by the following i andgnafter in f excess of i the thickness desired for the finished plate. The

plate, thus formed, may be reheatedand annealed, or reheated to 'belowwthe critical temperature and .cooled. he side'of the pl then cleaned of all scale and. a around r a gas.

' After the carburization of the the absorption thereby of the desired {caron, the plate is carefully cooled, and freed of scale, the face protected by naceous covering, reheated forging temperature and forged to final thickness. The temperature considerably temperature, quenched, again reheated, but to a less degree than before and again again reheated to a point below its critical temperature, bent and cooled slowly;

point well below its critical temperature and quenched.

The f a zone call the front. j T e above described plate having a hardened front whose face is carburized and 'a tough back, may be produced by known variations from the and it will be understood'that our process is not limited to the specific process described for producing such a plate-5 and out process, well knownart An ngot. of any above its criticalface offers extraordinary resistance to flow. H

, our 1'nven-,

rol d 1mm 9. plate o eitherfquickly r. ate intended: for

again reheated to a above described process,

invention, in its broader aspect, does not include any process whatever for' producing such a plate as a necessary step of the rocess,

The plate produced by method is then drawn at" below 500 F. or above 1100 F. \Ve prefer, in the drawing operation, to heat the plate to a temperature of about 650 degrees F. This temperature being distinctly below the critical temperature, the cooling may e effected quickly or slowly. v

The effect of armor plate so treated upon a projectile is that the point penetrates a certain distance, but the arrest of motion is so. rapid that the rear of the shell is upset and broken, in contradistinction to the point, which was formerly broken up.

' Ne are aware that attempts have made to reduce the'excessive brittleness o carburized face-hardened armor plates,with sacrifice of but little of the hardness, by drawing at temperatures up to say 3 de rees Ffor thereabouts, but our process di ers in that a far greater degree of hardness is relinquished for the corresponding gain in toughness;

This application is a continuation in part of our application for patent for improvement in'armor plate and process of making same, filed by us October 29th, 1920, Serial No. 120,483.,

Having now the above known a temperature not been fully described our inven- 00 a stiff hardened front with tion, what we claim and desire toprotect by Letters- Patent is- 1. The process of so as to render it resistant to which comprises treating the plate to produce a hardened front with a carburize face and a tough back, and then drawing the plate at a temperature not below 500' degrees F. or above 1100 degrees F., thereby removing from the front practically all its brittleness and a large portion of its hardness, while maintaining the stiffness required to offer extraordinary resistance to displacement.

treating armor plate penetration,

2; The process of making armor plate;

comprising treating an armor plate having a hardened front with carburi'zed a tough back by drawing said plate at a temperature of between 500 degrees F; and

f 1100 degrees F.

3,. As a new article of manufacture, an armor plate provided with a tough back and facev from which front the normal brittleness has been substantially removed and whose normal hardness has been substantially diminished.

In testimony of hereunto set our hands, at this 21st day' of June, 1922;

which invention, we have Philadelphia, on

FRANCIS BRADLEY.

HARRY L. FREV ERTM face and 

